Photovoltaic manufactures have made solar cells capable of generating electricity, but the mounting of these solar cells to buildings with pre-engineered roofing systems that have limitations on roof loads has at times been problematic. For example, many building owners seeking to install solar cells onto the roofs of their buildings are dismayed to hear that the building was not originally designed to accommodate the load of newly installed solar panels which can add weight in the range of 2-5 pounds per square foot. Current installations of a photovoltaic system over the top off an existing roof, often times requires a professional engineer to certify that the roof can support the increased load.
In addition, fire codes in many jurisdictions require a path to the ridge without requiring the firefighter to cross over photovoltaic systems. These new codes require access along the rakes, valleys and ridge of the roof and the ability to punch a hole in the ridge, to release dangerous gases. So long as a solar panel is receiving sunlight, it is impossible to turn off. During daylight, there can be enough voltage and current to injure or even kill a firefighter who comes in contact with the energized conductors.
The thin film photovoltaic industry has designed photovoltaic cells to be adhered to metal and rubber membranes used in manufacturing roofing materials. Adhering photovoltaic laminates directly to existing roof systems makes it very difficult and at times impossible to service the photovoltaic system, and the roof system without total replacement of each system. In addition, adhering photovoltaic panels directly to the roof system can result in accelerated corrosion of roof components. If a photovoltaic cell on a roof panel malfunctions it will diminish the power of the panels connected to that series. This will drastically reduce the output of the whole system. The wiring together of these thin film cells is critical in the system design. For optimal performance of the photovoltaic system, it must be possible to replace malfunctioning photovoltaic cells, in the same physical location to accommodate wiring logistics. One cannot simply work around a malfunctioning photovoltaic roof panel without rewiring the complete system to even out the number of cells in each series. Scraping off an adhesively adhered photovoltaic cell from a roof panel in a manner so as to reuse the metal panel is also not generally an option as the adhesive powerfully binds the photovoltaic to the roof panel. Alternatively, removing a standard metal roof panel secured in position with concealed fasteners, in order to remove the photovoltaic cell, is not cost effective and generally multiple panels must be removed in order to replace one. Consequently, a system for expedited installation and replacement of roof mounted photovoltaic cells remains a significant need in the industry.